Low end or old? They're very fundamentally different propositions. Low end but current cards could work. Low end and old probably won't be usable no matter how many of them you have.
–
allquixoticApr 8 '13 at 18:00

what do you plan on using the graphics cards for?
–
KeltariApr 8 '13 at 19:01

3 Answers
3

New/Old vs. High-end/Low-end

New/Old

More importantly than the release date of the card, what was the original release date of the microarchitecture that the GPU is based on?

Benefits/Drawbacks

A new card (latest generation microarchitecture, or immediately previous one) will generally see:

More frequent and significant driver updates and improvements from the vendor

More graphics capability for a given cost, electricity usage, and heat dissipation than older cards

Better compatibility with the advanced "eye candy" graphics features in the latest games; some games won't run at all on older cards

An old card will generally see:

Lack of driver updates, or the updates that do appear are only bug fixes

Better support on open source graphics drivers on Linux (primarily true of AMD/Nvidia cards, not so much Intel)

Higher power consumption, especially when compared to new cards at "idle" workload (nothing going on)

Better support for older motherboards and power supplies than newer cards

Worse support for the latest operating system releases than newer cards, with an increased incidence of performance problems and/or bugs the greater the number of days between the original release of the GPU's microarchitecture family and the release of the operating system

High-end/Low-end

Definition:

How expensive is the card relative to other cards, by the same manufacturer, which were released around the same time?

How "big" (physically and logically) is the card: is its GPU core scaled back in the number of cores it has, relative to cards which were released around the same time (same generation)?

Greater "longevity" (how long will the card last until it is really obsolete?) compared to low-end cards of the same generation -- although, buying high-end cards that are already several generations old is generally a waste of money, as current-generation low-end cards can be cheaper and provide better performance and features.

Tendency to be able to enable very high-end "eye candy" graphics features on games which were released around the same time as the card, although it may struggle with the advanced settings of games which are much newer than the card

Tendency to yield poor performance on the very latest "AAA" (high-end) games, even when using the latest generation microarchitecture

Good bargain between the features you get and the cost you pay

Quiet operation, and can fit in smaller cases or cramped cases where high-end cards won't fit

Advice Dog

Taking into account that even many recently-released games do not take full advantage (if any) of more than one logical GPU:

One new and high-end card will be an expensive up-front purchase, consume lots of power, require up-to-date motherboard and power supply, ample room in the case, but will provide worry-free, high-performance gaming; anything you throw at it for the next 3-4 years will run fine even on the highest or almost highest settings

One new and low-end card will be an affordable up-front purchase, consume very little power, require up-to-date motherboard and power supply, and struggle with performance if enabling the "Ultra" graphics features in games, but can run in a small case, will provide support for the latest graphics API for several years, and won't be obsolete as soon as older cards.

Multiple new and low-end cards will be a moderate up-front purchase, consume a moderate amount of power, require up-to-date motherboard and power supply, may or may not improve performance over a single card, but can run in a small case with multiple PCI-E slots, will provide support for the latest graphics API for several years, and won't be obsolete as soon as older cards.

One old and high-end card will be an expensive up-front purchase (if you buy it when it's new) or a moderate up-front purchase (if you buy it when it's old), consume a high amount of power, require a high capacity power supply, may struggle with the latest games, may not have actively maintained drivers, but will provide great performance on most games released up until 2 years ago, and might provide better performance per dollar than a single new, low-end card (depends on how "old" is old).

Multiple old and high-end cards will offer similar costs and benefits as a single card, but with even less benefit than multiple new cards, due to recent improvements in multi-card scalability.

One old and low-end card will suck for anything but basic web surfing or very old games. Period.

Sites like TechReport and AnandTech occasionally do roundups to compare low-end graphics cards. Suggest starting with the review sites and looking for information concerning the specific cards you are considering.

In theory Crossfire/SLI could offer up to 100% improvement (aka 2x) over a single card. In reality it will be quite a bit lower. If price is a controlling factor than I would recommend a good single card over two low-end ones.